Flank may refer to:

• Flank, the side of either a horse or a military unit
• Flanking maneuver in military tactics
• Flank, a region of the posterior torso (lower back) beneath the ribs and above the ilium
• Flank, a specific position in rugby union, Australian rules football and American football
• Flank steak, a specific cut of beef
• Flank speed, the maximum possible speed of a ship, faster than full speed